/*
 * Copyright (c) 2003, 2013, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
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 */

package com.sun.imageio.plugins.wbmp;

import java.util.Locale;
import javax.imageio.spi.ImageReaderSpi;
import javax.imageio.stream.ImageInputStream;
import javax.imageio.spi.IIORegistry;
import javax.imageio.spi.ServiceRegistry;
import java.io.IOException;
import javax.imageio.ImageReader;
import javax.imageio.IIOException;
import com.sun.imageio.plugins.common.ReaderUtil;

public class WBMPImageReaderSpi extends ImageReaderSpi {

  private static final int MAX_WBMP_WIDTH = 1024;
  private static final int MAX_WBMP_HEIGHT = 768;

  private static String[] writerSpiNames =
      {"com.sun.imageio.plugins.wbmp.WBMPImageWriterSpi"};
  private static String[] formatNames = {"wbmp", "WBMP"};
  private static String[] entensions = {"wbmp"};
  private static String[] mimeType = {"image/vnd.wap.wbmp"};

  private boolean registered = false;

  public WBMPImageReaderSpi() {
    super("Oracle Corporation",
        "1.0",
        formatNames,
        entensions,
        mimeType,
        "com.sun.imageio.plugins.wbmp.WBMPImageReader",
        new Class[]{ImageInputStream.class},
        writerSpiNames,
        true,
        null, null, null, null,
        true,
        WBMPMetadata.nativeMetadataFormatName,
        "com.sun.imageio.plugins.wbmp.WBMPMetadataFormat",
        null, null);
  }

  public void onRegistration(ServiceRegistry registry,
      Class<?> category) {
    if (registered) {
      return;
    }
    registered = true;
  }

  public String getDescription(Locale locale) {
    return "Standard WBMP Image Reader";
  }

  public boolean canDecodeInput(Object source) throws IOException {
    if (!(source instanceof ImageInputStream)) {
      return false;
    }

    ImageInputStream stream = (ImageInputStream) source;

    stream.mark();
    try {
      int type = stream.readByte();   // TypeField
      int fixHeaderField = stream.readByte();
      // check WBMP "header"
      if (type != 0 || fixHeaderField != 0) {
        // while WBMP reader does not support ext WBMP headers
        return false;
      }

      int width = ReaderUtil.readMultiByteInteger(stream);
      int height = ReaderUtil.readMultiByteInteger(stream);
      // check image dimension
      if (width <= 0 || height <= 0) {
        return false;
      }

      long dataLength = stream.length();
      if (dataLength == -1) {
        // We can't verify that amount of data in the stream
        // corresponds to image dimension because we do not know
        // the length of the data stream.
        // Assuming that wbmp image are used for mobile devices,
        // let's introduce an upper limit for image dimension.
        // In case if exact amount of raster data is unknown,
        // let's reject images with dimension above the limit.
        return (width < MAX_WBMP_WIDTH) && (height < MAX_WBMP_HEIGHT);
      }

      dataLength -= stream.getStreamPosition();

      long scanSize = (width / 8) + ((width % 8) == 0 ? 0 : 1);

      return (dataLength == scanSize * height);
    } finally {
      stream.reset();
    }
  }

  public ImageReader createReaderInstance(Object extension)
      throws IIOException {
    return new WBMPImageReader(this);
  }
}
